As a flowmeter for measuring the mass flow rate of a measurement target gas flowing in a main path, there is a thermal type flowmeter. Such a flowmeter is configured such that a portion of a measurement target gas flowing in a pipe, which is a main path, is taken into a sub path and is guided to a flow rate measurement unit. In the flow rate measurement unit, a hot wire, a silicon element, or the like is disposed and the mass flow rate in the pipe is measured by using a fact that the hot wire, the silicon element, or the like is cooled by an air stream and the electrical resistivity changes.
In PTL 1, a technique of an thermal type flowmeter, in which a static electricity dissipation region is provided in a bypass path and electric charge of the corrupting substance is eliminated in viewpoint of a countermeasure against corruption for preventing a corrupting substance from adhering to the flow rate measurement unit, is proposed (PTL 1).